1. Field of the Invention
The present invention relates to a fixing device and a fixing method in which an image is fixed onto a recording medium while supplying power to a heat source from a storage device, and to an image forming apparatus including the fixing device.
2. Discussion of the Related Art
An electrophotographic image forming apparatus, such as a copying machine, a printer, a facsimile machine, or other similar image forming apparatus, includes a fixing device that fixes a toner image formed on a recording media, such as a transfer sheet, with heat and pressure. The fixing device generally includes a fixing member, such as, a fixing roller and a fixing belt, and a pressing member, such as, a pressing roller, a pressing belt, and a pressing pad, which press-contacts the fixing member. The fixing member and pressing member cooperate to fix a toner image on a transfer sheet with heat and pressure while the transfer sheet passes through a nip part between the fixing member and pressing member.
Published Japanese patent application No. 3-36579 describes a heating device for use in a fixing device including a heater that heats by being supplied with power via a heater drive device. The heater drive device includes a chargeable storage battery, and a charger connected to a commercial power source for charging the storage battery. The heater includes a main heater powered by the commercial power source and an auxiliary heater powered by the storage battery. The storage battery is selectively connected to the charger in the form of a charging circuit or to the auxiliary heater in the form of a discharging circuit.
Further, Published Japanese patent application No. 2000-98799 describes a heating device for use in a fixing device including a heater that heats by being supplied with power, and a heater drive device for feeding power to the heater. The heater drive device includes a chargeable storage battery, and a charger connected to a commercial power source for charging the storage battery. The heater includes a main heater powered by the commercial power source and an auxiliary heater powered by the storage battery. The storage battery is charged when the main heater is turned off.
In a background fixing device, a surface temperature of a fixing member may fall to a lower limit of a fixing temperature or less even though a heater or a heat source is powered by a storage device. In this condition, a fixing failure typically occurs.
Therefore, it is desirable to provide a fixing device for use in an image forming apparatus that prevents a fixing failure.
Further, it is desirable to provide a method of fixing an image formed on a recording medium without a fixing failure.